Covalent surface modification of two-dimensional metal carbides

A method of modifying a surface termination of an MXene, the method comprising:

• providing particles of a first MXene represented by the formula Mm+1XmTn1 and having a layered structure in which the Mm+1Xm form two-dimensional sheets, where M is a transition metal, X is carbon, m is 1, 2, or 3, and Tn1 denotes surface terminating chloride anions, bromide anions, iodide anions or a combination thereof;
• dispersing the particles of the first MXene in an alkali halide molten salt bath comprising an alkali chloride salt, an alkali bromide salt, an alkali iodide salt, or a eutectic thereof and containing solubilized non-halide anions, the solubilized non-halide anions characterized in that a bond formed between the non-halide anion and the transition metal of the first MXene is stronger than a bond formed between the surface terminating chloride anion, bromide anion, or iodide anion and the transition metal of the first MXene, whereby the non-halide anions replace surface terminating chloride anions, bromide anions, or iodide anions on the first MXene via a halide exchange reaction under temperature of 300° C.-700° C. to form a second MXene represented by the formula Mm+1XmTn2 and having a layered structure in which the Mm+1Xm form two-dimensional sheets, where M is the transition metal, X is carbon, m is 1, 2, or 3, and Tn2 comprises surface terminating non-halide anions.